<template>
  <!-- 商品分类导航 -->
  <div class="type-nav">
    <div class="container">
      <div @mouseenter="mouseenterTit" @mouseleave="mouseleaveTit">
        <h2 class="all">全部商品分类</h2>
        <transition name="nav">
          <div class="sort" v-show="isShow">
            <div class="all-sort-list2" @mouseleave="currentIndex = -1">
              <div
                class="item"
                v-for="(category, index) in categoryList"
                :key="category.categoryId"
                :class="currentIndex === index ? 'active' : ''"
                @mouseenter="throttleEnter(index)"
                @click="toSearch"
              >
                <h3>
                  <a
                    :data-category1Id="category.categoryId"
                    :data-categoryName="category.categoryName"
                    >{{ category.categoryName }}</a
                  >
                </h3>
                <div class="item-list clearfix">
                  <div class="subitem">
                    <dl
                      class="fore"
                      v-for="child in category.categoryChild"
                      :key="child.categoryId"
                    >
                      <dt>
                        <a
                          :data-category2Id="child.categoryId"
                          :data-categoryName="child.categoryName"
                          >{{ child.categoryName }}</a
                        >
                      </dt>
                      <dd>
                        <em
                          v-for="item in child.categoryChild"
                          :key="item.categoryId"
                        >
                          <a
                            :data-category3Id="item.categoryId"
                            :data-categoryName="item.categoryName"
                            >{{ item.categoryName }}</a
                          >
                        </em>
                      </dd>
                    </dl>
                  </div>
                </div>
              </div>
            </div>
          </div>
        </transition>
      </div>
      <nav class="nav">
        <a href="###">服装城</a>
        <a href="###">美妆馆</a>
        <a href="###">尚品汇超市</a>
        <a href="###">全球购</a>
        <a href="###">闪购</a>
        <a href="###">团购</a>
        <a href="###">有趣</a>
        <a href="###">秒杀</a>
      </nav>
    </div>
  </div>
</template>

<script>
import _ from "lodash";
import { mapState } from "vuex";
export default {
  name: "NavType",
  data() {
    return {
      currentIndex: -1,
      isShow: false,
    };
  },
  mounted() {
    /* 
      2.必须只能调用一次_.throttle方法,得到一个真正的事件函数,所有的列表全部用的都是这个函数
      _.throttle方法返回的函数可以接受参数,并传递给核心函数mouseenter
    */
    this.throttleEnter = _.throttle(this.mouseenter, 30, {
      trailing: false,
      leading: true,
    });

    //3.初始化的时候判断当前的路径,决定是否展示三级列表
    this.isShowUpdate();
  },
  methods: {
    //1.三级列表鼠标移入事件
    mouseenter(index) {
      this.currentIndex = index;
    },

    //2.三级列表每个元素的编程式路由导航
    toSearch(e) {
      if (e.target.nodeName === "A") {
        const query = {};
        const { category1id, category2id, category3id, categoryname } =
          e.target.dataset;

        query.categoryName = categoryname;

        if (category1id) {
          query.category1Id = category1id;
        } else if (category2id) {
          query.category2Id = category2id;
        } else if (category3id) {
          query.category3Id = category3id;
        }

        //获取当前有没有params
        const params = this.$route.params;

        this.$router.push({
          // path: "/search",
          name: "search",
          query: query,
          params,
        });
      }
    },

    //3.判断当前路径,决定isShow的值
    isShowUpdate() {
      if (this.$route.path === "/home") {
        this.isShow = true;
      }
    },

    mouseenterTit() {
      if (this.$route.path === "/home") return;
      this.isShow = true;
    },
    mouseleaveTit() {
      if (this.$route.path === "/home") return;
      this.isShow = false;
    },
  },
  computed: {
    ...mapState("home", ["categoryList"]),
  },
  watch: {
    $route: {
      handler() {
        this.isShow = false;
      },
    },
  },
};
</script>

<style lang="less" scoped>
//定义动画样式
.nav-enter,
.nav-leave-to {
  opacity: 0;
}

.nav-enter-active,
.nav-leave-active {
  transition: all 0.2s linear;
}

.type-nav {
  border-bottom: 2px solid #e1251b;

  .container {
    width: 1200px;
    margin: 0 auto;
    display: flex;
    position: relative;

    .all {
      width: 210px;
      height: 45px;
      background-color: #e1251b;
      line-height: 45px;
      text-align: center;
      color: #fff;
      font-size: 14px;
      font-weight: bold;
    }

    .nav {
      a {
        height: 45px;
        margin: 0 22px;
        line-height: 45px;
        font-size: 16px;
        color: #333;
      }
    }

    .sort {
      position: absolute;
      left: 0;
      top: 45px;
      width: 210px;
      height: 461px;
      position: absolute;
      background: #fafafa;
      z-index: 999;

      .all-sort-list2 {
        .item {
          h3 {
            line-height: 30px;
            font-size: 14px;
            font-weight: 400;
            overflow: hidden;
            padding: 0 20px;
            margin: 0;

            a {
              color: #333;
            }
          }

          .item-list {
            display: none;
            position: absolute;
            width: 734px;
            min-height: 460px;
            background: #f7f7f7;
            left: 210px;
            border: 1px solid #ddd;
            top: 0;
            z-index: 9999 !important;

            .subitem {
              float: left;
              width: 650px;
              padding: 0 4px 0 8px;

              dl {
                border-top: 1px solid #eee;
                padding: 6px 0;
                overflow: hidden;
                zoom: 1;

                &.fore {
                  border-top: 0;
                }

                dt {
                  float: left;
                  width: 54px;
                  line-height: 22px;
                  text-align: right;
                  padding: 3px 6px 0 0;
                  font-weight: 700;
                }

                dd {
                  float: left;
                  width: 415px;
                  padding: 3px 0 0;
                  overflow: hidden;

                  em {
                    float: left;
                    height: 14px;
                    line-height: 14px;
                    padding: 0 8px;
                    margin-top: 5px;
                    border-left: 1px solid #ccc;
                  }
                }
              }
            }
          }

          &.active {
            background: paleturquoise;
            .item-list {
              display: block;
            }
          }
        }
      }
    }
  }
}
</style>